- ZT3100: 1'shaft, 1yr commercial warranty. (Stander B)
- ZT3200: 1.25'shaft, shock valves, 2yr commercial warranty.
- ZT3400: Better gear options, black paint. (Wright ZTO)
- ZT3600: Larger charge pump, all steel gears, different rotating group.
- ZT4400: Wider gear set.
- ZT5400: Planetary reduction.